Fair enough; please pardon my ignorance on that score. Am I right, though, that rolling below the target number (2e AC being an example) was the goal of DnD until 3e came along? Point being, I'm sure we could find lots of sacred cows that 3e slew for the greater good.
There's a very big difference between sacred cows that have been done away with by changing the way the system's math works (the classic 5 Saving Throws, or descending AC, for example) and those which represent something fundamental about D&D. Most of what gets changed from edition to edition is something fiddly - like how skills work, or which (non-core) classes are in the game, or how a particular spell works.
For instance, Dungeons & Dragons has never had a well-defined skill system, so creating one (and fiddling with it) doesn't do away with any sacred cows. By contrast, Vancian magic ranks right up there with the arcane/divine magic divide as sacred cows go. Sure, both are pretty idiosyncratic to D&D and D&D only (although some elements have been widely adopted in other pop culture due to D&D's influence), but that's also why they're iconic TO D&D - "sacred cows," if you will. And like the 6 attributes, like AC & Hit Points, like rolling for initiative, like the d20 to attack, like rolling for damage, and like the class-based character creation, it just wouldn't have that "D&D feel" for a large number of people if you take them out.
Personally, I would happily ditch
both Vancian spellcasting and the arcane/divine magic divide in favor of a more universal system that was less D&D flavor-specific. But I know that can be, at best, an option, because to some, Vancian spellcasting and the arcane/divine magic divide are true "sacred cows" - NECESSARY components for maintaining that "D&D feel" for a large number of people.